@RoryAlsop -- Not duplicate because the other question is for biting flies. Not all bugs are repelled with the same methods (for instance DEET is only so-so against ticks in my experience). However, thank you for explaining why you voted to close
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Russell Steen♦Feb 9 '12 at 1:30

The latest treatment I've seen is Permethrin. You spray it on your clothes, not on your skin, so it may be better for people with skin issues. I'm only posting a comment because I don't have any facts to back this up.
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BMitchOct 16 '12 at 2:32

Of the active ingredients registered with the EPA, CDC believes that two have demonstrated a higher degree of efficacy in the peer-reviewed, scientific literature (See Publications page.). Products containing these active ingredients typically provide longer-lasting protection than others:

DEET (N,N-diethyl-m-toluamide)

Picaridin (KBR 3023)

Oil of lemon eucalyptus [active ingredient: p-menthane 3,8-diol (PMD)], a plant- based repellent, is also registered with EPA. In two recent scientific publications, when oil of lemon eucalyptus was tested against mosquitoes found in the US it provided protection similar to repellents with low concentrations of DEET.

**: Caveat emptor:

“Pure” oil of lemon eucalyptus (essential oil) is not the same product; it has not undergone similar, validated testing for safety and efficacy, is not registered with EPA as an insect repellent, and is not covered by this recommendation.